Heated lens lighting arrangement

ABSTRACT

According to aspects of the embodiments, a lighting fixture is designed to help prevent the accumulation of snow or ice on the light emitting face (e.g., lens) of the lighting fixture. The lighting fixture harvests both the light and heat generated by at least one light source, such as but not limited to at least one LED light source. The lighting fixture adopts a flip-mount light source mounting design in which one side of a passive heat exchanger is mounted or secured closely adjacent or proximate to the lens, and the light source is mounted or secured to another side of the passive heat exchanger. The heat generated by the light source is conducted by the passive heat exchanger to heat the lens. Additionally, the light emitted from the light source is redirected back through the passive heat exchanger and to the lens using a bundle of light fiber cables.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional patentapplication Ser. No. 14/915,468, filed Feb. 29, 2016, which is the 35U.S.C. § 371 national stage of PCT Application No. PCT/US2014/053503,filed Aug. 29, 2014, which claims priority to and the benefit of U.S.Provisional Application No. 61/872,562, filed Aug. 30, 2013, the entirecontents of all of which applications are hereby incorporated herein byreference in their entirety.

BACKGROUND

Incandescent light bulbs generally produce light by passing currentthrough a wire filament. The wire filament is heated by the current to arelatively high temperature and outputs heat and light. It is noted thatincandescent light bulbs are relatively less efficient than other typesof bulbs. Some incandescent light bulbs convert less than five percentof energy into visible light, with the remaining energy being wasted asheat. In some cases, the heat generated by incandescent light bulbs isused or relied upon for a particular purpose. For example, the heatgenerated by incandescent light bulbs may be relied upon to melt snow orice on outdoor lighting fixtures.

Because of the relatively low cost and wide range of incandescent lightbulbs available, incandescent light bulbs are widely used forresidential, commercial, and municipal lighting, although newer, morecost effective and efficient light sources are being adopted. Due inpart to their relative inefficiency, incandescent light bulbs are nowbeing replaced by other light bulbs, lamps, or devices, such asfluorescent lamps (e.g., including but not limited to compactfluorescent lamps, cold cathode fluorescent lamps, etc.), high intensitydischarge lamps, and light-emitting diodes.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the embodiments and the advantagesthereof, reference is now made to the following description, inconjunction with the accompanying figures briefly described as follows:

FIG. 1 illustrates a lighting fixture according to an example embodimentdescribed herein.

FIG. 2 illustrates a passive heat exchanger and light source of thelighting fixture in FIG. 1 according to an example embodiment describedherein.

FIG. 3 individually illustrates the passive heat exchanger, the lightsource, and the light collector of the lighting fixture in FIG. 1according to an example embodiment described herein.

FIG. 4 illustrates the passive heat exchanger of the lighting fixture inFIG. 1 according to an example embodiment described herein.

FIG. 5 illustrates another passive heat exchanger according to theembodiments described herein.

FIG. 6 illustrates an example embodiment of a lens and a passive heatexchanger including semispherical surfaces according to one embodimentdescribed herein.

The drawings illustrate only example embodiments and are therefore notto be considered limiting of the scope of the embodiments describedherein, as other embodiments are within the scope of this disclosure.The elements and features shown in the drawings are not necessarilydrawn to scale, emphasis instead being placed upon clearly illustratingthe principles of the embodiments. Additionally, certain dimensions orpositionings may be exaggerated to help visually convey certainprinciples. In the drawings, similar reference numerals between figuresdesignate like or corresponding, but not necessarily the same, elements.

DETAILED DESCRIPTION

In the following paragraphs, the embodiments are described in furtherdetail by way of example with reference to the attached drawings. Theembodiments are not to be considered limited in structure, form,function, or application to the examples set forth herein.

Certain types of lighting fixtures are designed for use outdoors. Theselighting fixtures are generally designed to withstand exposure toweather including cycles of heat and cold. It is noted that some outdoorlighting fixtures, such as traffic lights, crosswalk lights, lightedstreet signs, etc, are used for traffic and/or pedestrian signaling. Thebuildup of snow or ice on such outdoor lighting fixtures may present orcause a dangerous situation if the light provided by such fixtures isblocked or covered by the buildup of snow or ice.

As noted above, incandescent light bulbs generally produce light bypassing current through a wire filament. The wire filament is heated bythe current to a relatively high temperature and outputs heat and light.In the case of an outdoor lighting fixture including an incandescentlight bulb, the heat generated by the incandescent light bulb can berelied upon, at least in part, to melt any snow or ice that accumulateson the fixture during the winter.

Light emitting diode (LED) light sources have advantages overconventional incandescent, fluorescent, and high intensity discharge(HID) light sources, such as relatively higher energy efficiency, longerlife, lower profiles, and environmental benefits. It is expected thatLEDs will displace the use of other light sources in many applications.For example, LEDs are being relied upon in outdoor lighting fixtures toa greater extent. In this context, outdoor LED lighting fixtures mayinclude traffic signals, rail signals, post-top luminaires, highway poleand high-mast lights, area lighting fixtures, tunnel lightingluminaires, architectural lighting fixtures, etc.

While LED light sources offer increased lifetimes (e.g., about50,000-100,000 hours) as compared to other light sources, LEDs producerelatively less waste heat, comparatively. Thus, as incandescent lightbulbs are now being replaced in outdoor lighting fixtures by moreefficient light sources, such as but not limited to LEDs, generally lessheat is available to help with melting snow or ice.

LED light sources also differ from conventional incandescent light bulbswith regard to the manner of light emission and heat generation.Conventional light sources such as incandescent and HID bulbs, forexample, radiate light and heat in the same direction. The heatgenerated by an LED light source, however, is not radiated in the samedirection as the light. Instead, relatively more heat is provided at theback of the diode itself. This heat is generally conducted away from theLED light source using a heat exchanger. This may lead to a problem insome lighting fixtures if the heat generated by LEDs is trapped orcontained to the back of the fixture. In this case, insufficient heatmay be provided or directed toward the lens of the fixture to preventthe accumulation of snow and ice that may cover or block it.

In the context outlined above, according to aspects of the embodiments,a lighting fixture is designed to help prevent the accumulation of snowor ice on the light emitting face (e.g., lens) of the lighting fixture.In one embodiment, the lighting fixture harvests both the light and heatgenerated by a light source, such as but not limited to an LED lightsource. The lighting fixture adopts a flip-mount light source mountingdesign in which one side of a passive heat exchanger is mounted closelyadjacent or proximate to the lens, and the light source is mounted orsecured to another side of the passive heat exchanger. The heatgenerated by the light source is conducted away from the light source bythe passive heat exchanger to heat the lens. Additionally, the lightemitted from the light source is redirected back through the passiveheat exchanger and to the lens using a bundle of light fiber cables.

As a result of substantial overlap in the surface area of the passiveheat exchanger that is proximate to the lens, the temperature of thelens may be maintained above freezing, resulting in the ability to meltsnow and ice in wintery conditions. Based on the principles describedherein, outdoor lighting fixtures are able to melt snow and ice to agood extent using the nominal amount of heat produced by a light source,such as but not limited to an LED light source, without the need foradditional heat generators or the associated sensors to control them. Inthis sense, the embodiments, concepts, and principles described hereinmay be relied upon to help reduce or prevent the accumulation of snow orice on the light emitting faces of lighting fixtures at a lower overallcost.

Turning to the drawings, various aspects of the embodiments aredescribed in further detail.

FIG. 1 illustrates a lighting fixture 10 according to an exampleembodiment described herein. The lighting fixture 10 includes a lightingfixture housing 110, a lens 120, a passive heat exchanger 130, a lightsource 140, a light collector 150, and a light fiber bundle 160. Thelighting fixture 10 may be representative of a portion of a trafficsignal light, for example, but it should be appreciated that thestructures, principles, and concepts described herein are applicable toany type of lighting fixture, whether used indoors or outdoors. Thelighting fixture housing 110 provides an overall housing for thelighting fixture 10 and, generally, secures the lens 120 and the passiveheat exchanger 130, among other parts of the lighting fixture 10, intoplace.

According to aspects of the embodiments, the lens 120 of the lightingfixture 10 is heated by way of the passive heat exchanger 130 using heatdissipated from the light source 140. As described in further detailbelow, this heat energy is conducted away from the light source 140 bythe passive heat exchanger 130 and ultimately provided to the lens 120.Because the lens 120 is secured by the lighting fixture housing 110 in aposition proximate to the passive heat exchanger 130, as illustrated inFIG. 1, the heat conducted away from the light source 140 by the passiveheat exchanger 130 is passed on or provided to the lens 120. To arelatively large extent, this heat is provided to the lens 120 evenlyand to its outer edges.

The lens 120 may be formed from any suitable material including glass orplastic, for example. In various embodiments, the lens 120 may take anysuitable size and/or shape depending upon the intended use for thelighting fixture 10, among other considerations. The passive heatexchanger 130 may be formed from aluminum, copper, an aluminum-copperalloy, or any other composition suitable for conducting heat away fromthe light source 140. Depending on the ambient environment, the passiveheat exchanger 130 may be formed at least in part using iron or steel,as iron and steel stores heat. Also, the passive heat exchanger 130 mayinclude one or more anodized surfaces to facilitate heat absorption anddistribution. The passive heat exchanger 130 may take any suitable sizeand/or shape, again, depending upon the intended use for the lightingfixture 10, among other considerations. In some embodiments, the passiveheat exchanger 130 may include one or more fins on the back for fastheat conduction away from the light source 140, as necessary.

As illustrated in FIG. 1, a space “A” remains between the passive heatexchanger 130 and the lens 120, with the passive heat exchanger 130 andthe lens 120 being secured proximately to each other. In variousembodiments, this space “A” may be a small as 0 inches (e.g., contact)or larger than about ⅛ inch. In the preferred embodiments, the space “A”is about ⅛ inch. To the extent possible, the lighting fixture 10 may bedesigned such that the space “A” is substantially uniform across nearlythe entire adjacent surface areas of the lens 120 and the passive heatexchanger 130. As further described below, the width of the space “A”may be selected based on a balance between the ability for heat exchangebetween the lens 120 and the passive heat exchanger 130 and the abilityfor light carried by the light fiber bundle 160 to disperse or diffusebefore crossing the lens 120.

As illustrated in FIG. 1, the light fiber bundle 160 includes aplurality of light fiber cables 160A-160D bundled together by the lightcollector 150. It should be appreciated that the lighting fixture 10 inFIG. 1 is representative and may include additional or fewer light fibercables in the light fiber bundle 160. As further discussed below, thelighting fixture 10 may include nineteen light fiber cables, althoughother numbers of light fiber cables may be relied upon depending uponthe total light output and/or size of the lighting fixture 10, forexample, among other considerations.

The light collector 150 bundles the light fiber cables 160A-160Dtogether and secures them proximate to or against the light-emittingside of the light source 140. In this context, each of the plurality oflight fiber cables 160A-160D extends from the light source 140 at afirst distal end to a corresponding aperture in and through the passiveheat exchanger 130 at a second distal end, as illustrated in FIG. 1. Atthe second distal end of each of the plurality of light fiber cables160A-160C, an end fitting (e.g., see reference 162) is inserted into acorresponding aperture. Each end fitting may be secured within itscorresponding aperture using friction, a mechanical connection (e.g.,screw, fastening plate, etc.), an adhesive, any other suitable means, orany or combination thereof. Here, it should be appreciated that,although only the light fiber cables 160A-160C are illustrated in FIG. 1as being inserted into an aperture in the passive heat exchanger 30,each light fiber cable in the lighting fixture 10 would be inserted intoa corresponding aperture. The apertures in the passive heat exchanger130 are further described below with reference to FIG. 2.

Each of the light fiber cables 160A-160D may be embodied as a flexiblefiber optic light guide including one or more glass or quartz lightguide fibers sheathed in a plastic or PVC-covered monocoil or metalhose, for example. In various embodiments, the light fiber cables160A-160D may vary in diameter. For example, the light fiber cables160A-160D may vary in diameter from about ⅛ inch to about ¾ inch orlarger, although the use of other diameters of light fiber cables iswithin the scope of the embodiments. Generally, the light fiber cables160A-160D are selected to be the shortest practical length based on thesize of the lighting fixture 10, although it is noted that the amount oflight lost in most suitable light fiber cables is mostly negligible forcables between 1 and 4 feet in length.

The number and diameter of the light fiber cables 160A-160D in the lightfiber bundle 160 (and apertures in the passive heat exchanger 130) maydepend on various factors, such as the number of light sources 140 usedin the lighting fixture 10, the shape and size of the passive heatexchanger 130, the size and optical characteristics of the light sources140 used in the lighting fixture 10, the uniformity of the luminancefrom the lens 120 (which may be required or set by codes and/orstandards), the transmission and refraction of the lens 120, and anyloss of light through the light fiber cables 160A-160D. Thus, the numberand diameter of the light fiber cables 160A-160D in the light fiberbundle 160 depends upon various factors. Additionally, the length of thelight fiber cables 160A-160D depends on the shape and size of thepassive heat exchanger 130 and size of the lighting fixture 10 and thelight fixture housing 110, among other factors. Within a relativelysmall space, the length of the light fiber cables 160A-160D may usuallybe less than about 1 foot.

The light source 140 may be embodied as an LED light source, althoughthe use of other light sources is within the scope of the embodiments.The light source 140 may be embodied as a high-power (e.g., 25, 50, 100,200 W, etc.) chip on board LED light source, for example, or anothersuitable type or structure of high output LED device. In variousembodiments, the light source 140 may provide warm or cool white orcolored light. For example, the light source 140 may provide a red,yellow, or green light for traffic signaling. The light source 140 mayalso provide a white light to illuminate a roadway, parking lot, orgarage, for example. Additionally or alternatively, the lens 120 may becolored.

As illustrated in FIG. 1, the back or heat-sinking side of the lightsource 140 is mounted to the passive heat exchanger 130. In thiscontext, the heat-sinking side of the light source 140 may be mounted tothe passive heat exchanger 130 at any suitable location and using anysuitable means. It is noted that the light source 140 should be mountedto the passive heat exchanger 130 securely, using screws, fasteners, oranother suitable attaching means, to ensure good heat transfer from thelight source 140 to the passive heat exchanger 130. As necessary,thermal pastes or other heat transfer facilitating compounds mayadditionally be relied upon.

Typically, the light source 140 should be mounted to the passive heatexchanger 130 at a location for nearly uniform distribution of heat inthe passive heat exchanger 130 away from the light source 140. Thus, thelight source 140 may, under most circumstances, be mounted proximate tothe center of the passive heat exchanger 130. If multiple light sourcesare relied upon in the lighting fixture 10, it should be appreciatedthat the light sources should be mounted to the passive heat exchanger130 at spaced-apart locations to distribute the heat away from each ofthe light sources relatively evenly throughout the passive heatexchanger 130.

In operation, once powered by a suitable power supply (not shown), thelight source 140 emits light 20 in a first direction away from the lens120. In turn, the light 20 is captured by the light collector 150 anddirected into the first distal ends of the light fiber cables 160A-160Dof the light fiber bundle 160. This light is then wrapped or directedaround and ultimately passed through the passive heat exchanger 130 bythe light fiber cables 160A-160D. Particularly, because the seconddistal ends of the light fiber cables 160A-160D extend through theapertures in the passive heat exchanger 130, the light 20 from the lightsource 140 is ultimately directed through the lens 120 as light 30.

Meanwhile, heat from the light source 140 conducts through the passiveheat exchanger 130. This heat, in turn, is passed on to the lens 120 dueto the proximity between the passive heat exchanger 130 and the lens120. Further, it is noted that, because the major surfaces of the lens120 and the passive heat exchanger 130 correspond in size, the greaterextent of the lens 120 is exposed to heat from the light source 140 byway of the passive heat exchanger 130. Once heated, the lens 120 maymelt any accumulation of snow or ice that may form on the outside of thelens 120 in cold conditions.

It should be appreciated that the lighting fixture 10 may be contrastedwith lighting fixtures that use heat generators (e.g., thermal wiresattached to the lens, infrared LEDs, etc.) and sensors to control themfor the purpose of melting snow or ice. Not only do thermal wiresconsume additional energy, but they also reduce the light transmittanceof the lenses. Integrated infrared LEDs also increase energyconsumption. In addition, these technologies impart additional costs andpoints of failure by using sensors and control systems to control theadditional generation of heat.

The embodiments described herein rely upon light sources, such as one ormore LED light sources, that generate both light and heat throughout areliable life of about 50,000-100,000 hours. One or more LED lightsources may be selected to provide the minimum amount of heat and lightfor suitable year round operations. For example, the LED light sourcesmay be selected to ensure that the surface temperature of the lightemitting face or lens of the lighting fixture is above the freezingtemperature of about 32° F. even in the winter, to avoid theaccumulation of ice, frost, and/or snow on or over the light emittingface. Further, the LED light sources may be selected to ensure that thebrightness and intensity of light output is higher than the thresholdvalues for roadway safety, such as AASHTO (American Association of StateHighway and Transportation Officials), IES (Illuminating EngineeringSociety), CIE (International Commission On Illumination), ANSI (AmericanNational Standards Institute), and state and local specifications.

Turning to the remaining figures, other aspects of the embodiments aredescribed in greater detail. FIG. 2 illustrates the passive heatexchanger 130 and light source 140 of the lighting fixture 10 in FIG. 1according to an example embodiment described herein. In FIG. 2, a frontor plan view of the passive heat exchanger 130 is shown on the left, anda side view of the passive heat exchanger 130 is shown on the rightalong with the light source 140, the light collector 150, and the lightfiber cable 160A. In connection with the front view of the passive heatexchanger 130, the apertures 132 of the passive heat exchanger 130 maybe more clearly seen. Generally, the diameter of each of the apertures132 is selected based on the diameter of the light fiber cables160A-160D in the light fiber bundle 160. Although not individuallyidentified, a total of nineteen apertures 132 may be identified in FIG.2. It should be appreciated, however, that the number of aperturesthrough the passive heat exchanger 130 may vary among embodiments.Typically, the number of apertures may depend upon the number of lightfiber cables in the light fiber bundle 160, which may depend uponvarious factors as described above. Additionally, mounting holes 134 formounting the light source 140 to the passive heat exchanger 130 areillustrated near the center of the passive heat exchanger 130.

FIG. 3 individually illustrates the passive heat exchanger 130, thelight source 140, and the light collector 150 of the lighting fixture 10in FIG. 1. In one embodiment, as illustrated in FIG. 3, the passive heatexchanger 130 includes a niche 136. The light source 140 may be mountedwithin the niche 136 so the heat accumulated on various surfaces (e.g.,both the back and side surfaces) of the light source 140 can beconducted away quickly. It should be appreciated, however, that theniche 136 may be omitted from the passive heat exchanger 130, and thelight source 140 may be flush mounted upon the passive heat exchanger130 and secured thereto using screws, bolts, nuts, or any other suitabletypes of fasteners has discussed above.

As illustrated in FIG. 3, the light collector 150 may include a lens 152to help focus and direct substantially all light from the light source140 to the first distal ends of the light fiber cables 160A-160D in thelight fiber bundle 160 (FIG. 1). The lens 152 may be embodied as aconvex lens formed from any suitable composition of optical glass, forexample.

In some embodiments, one or more of the light fiber cables in the lightfiber bundle 160 may include a light diffuser 162 fitted at its seconddistal end. The light diffuser 162 may be either secured to the seconddistal end of the light fiber cable, as the light diffuser 162 isillustrated as being attached to the second distal end of the lightfiber cable 160A in FIG. 3, or mounted or secured into one of theapertures in the passive heat exchanger 130. Each light diffuser 162 maybe embodied as a mini lens to adjust the distribution of light from alight fiber cable. For example, each light diffuser 162 may direct,diffuse, or disperse light from an end of a light fiber cable. In thiscontext, the use of light diffusers such as the light diffuser 162 mayhelp to spread or disperse the light 20 from the light source 142 over agreater area of the light emitting face (e.g., the lens 120) of thelighting fixture 10 (FIG. 1).

FIG. 4 illustrates the major (e.g., front and back) surfaces of thepassive heat exchanger 130 of the lighting fixture 10 in FIG. 1according to an example embodiment described herein. In FIG. 4, thefront of the passive heat exchanger 130 is shown on the right, across-sectional side view of the passive heat exchanger 130 is shown inthe center, and the back of the passive heat exchanger 130 is shown onthe left. In connection with the front and back views of the passiveheat exchanger 130, the apertures 132 of the passive heat exchanger 130may be more clearly seen. Additionally, mounting holes 134 for mountingthe light source 140 to the passive heat exchanger 130 are illustratednear the center of the passive heat exchanger 130.

With reference to FIG. 4, it should be appreciated that, although thepassive heat exchanger 130 is shown as being circular in FIG. 4, thepassive heat exchanger 130 may take other regular or irregular shapes,including multi-sided polygon, oval, etc. Generally, based on theconcepts of the embodiments described herein, at least one major surfaceof the passive heat exchanger 130 should be formed to correspond inshape and size with the light emitting surface (e.g., lens) of thelighting fixture. Additionally, as described in further detail belowwith reference to FIG. 6, the embodiments described herein encompasspassive heat exchangers having major surfaces that are curved as opposedto being generally flat as illustrated in FIG. 3. Further, theembodiments described herein encompass passive heat exchangers havingboth uniform and non-uniform (e.g., sloped) thicknesses.

Turning to FIG. 5, another passive heat exchanger 530 is illustratedaccording to the embodiments described herein. In FIG. 5, the front of apassive heat exchanger 530 is illustrated. The passive heat exchanger530 includes three mounting locations 536. The mounting locations 536are representative of locations that may be used for mounting multiplelight sources similar to the light source 120 described above withreference to FIGS. 1-3. In this context, it is noted that, if multiplelight sources are mounted to a passive heat exchanger, the light sourcesmay be mounted at spaced-apart locations on the passive heat exchangerto help evenly disperse heat from the light sources. It is additionallynoted that the passive heat exchanger 530 includes a plurality ofapertures 532. The positions of the apertures 532 in FIG. 5 arerepresentative only. In alternative embodiments, the positions of theapertures 532 may vary from that illustrated in FIG. 5. Similarly, thepositions of the apertures 132 may vary from the positions illustratedin FIGS. 2 and 4. In preferred embodiments, it is noted that theapertures may be evenly spaced to distribute light evenly.

FIG. 6 illustrates an example embodiment of a lens 620 and a passiveheat exchanger 630 including semispherical surfaces according to oneembodiment described herein. The side profile of the passive heatexchanger 630 is sloped with a gradually reduced thickness from thecenter to the edge.

In FIG. 6, it is noted that both the lens 620 and the passive heatexchanger 630 include a major semispherical surface. In this view, itcan be appreciated that the space “B” is substantially uniform over thefacing concave and convex semispherical surfaces of the lens 620 and thepassive heat exchanger 630, respectively. This uniformity leads touniform heat transfer from the passive heat exchanger 630 to the lens620 according to the concepts described herein. Additionally, as thelens 620 and the passive heat exchanger 630 are brought into positioncloser to each other, as illustrated in the exploded portion of the viewin FIG. 6, this uniformity in space (i.e., the space “C”) may bemaintained. As described above, in various embodiments, this space “C”may be smaller or larger than about ⅛ inch. In some embodiments, thespaces “A” (FIG. 1), “B,” or “C” may be filled with a gas for betterthermal performance.

Table 1 below includes a summary of laboratory test results using LEDlight sources of various colors (red, green, yellow) in a lightingfixture according to the embodiments described herein. The results showthe energy consumed by each LED in different ambient environments (e.g.,ambient temperature, relative humidity, air velocity) and the associatedsurface temperatures of the lens. The test results show that red LEDsconsume only about 16.9 to 20.7 watts to maintain the light emittingsurface temperature of the lens above the freezing temperature of about32° F. at an ambient temperature of 10° F., when connected to a trafficcontrol cabinet having an ON time of 44 seconds or longer. For greenLEDs, to maintain the light emitting surface temperature of the lensabove the freezing temperature of about 32° F. at an ambient temperatureof 10° F., the wattage is in a range of above 18.1 to 22.1 watts whenconnected to the traffic control cabinet having an ON time of 35 secondsor longer, but the wattage jumps to about 50.7 watts when the ON time is10 seconds. Similarly, for yellow LEDs, to maintain the light emittingsurface temperature of the lens above the freezing temperature of about32° F. at an ambient temperature of 10° F., the wattages is in a rangeof about 17.3 to 20.8 watts when the ON time is not limited, but thewattage jumps above 47.8 watts when the ON time is only 3 sec.

TABLE 1 Control Cabinet Lens Ambient Air Lens Time Cycle Wattage LEDLens gap Temp.(° F.) RH velocity temp.(° F.) On Time (W) Color Material(inch) Avg. % (m/s) Avg. STD (Sec) (Sec) Avg. Red Plastic 0.125 44.968.8 0.000 102.8 1.8 N/A N/A 48.0 Glass N/A 84.4 38.8 0.012 122.7 6.4N/A N/A 48.0 Plastic 0.125 8.9 44.8 0.012 51.2 1.7 N/A N/A 42.0 Plastic0.125 9.3 47.4 0.012 38.6 1.0 N/A N/A 21.0 Plastic 0.125 9.3 49.1 0.01230.0 0.9 N/A N/A 13.0 Plastic 0.125 7.3 39.8 N/A 56.4 3.5 N/A N/A 31.6Plastic 0.125 4.0 40.4 N/A 25.5 1.7 N/A N/A 12.5 Plastic 0.125 8.0 41.80.012 32.3 2.2 N/A N/A 16.9 Plastic 0.125 8.7 54.8 0.012 34.0 2.4 44 8220.7 Green Plastic 0.125 24.0 47.7 0.012 75.6 5.7 N/A N/A 47.8 Plastic0.125 50.3 62.8 0.012 150.6 5.2 N/A N/A 87.5 Glass N/A 80.0 49.5 0.012164.6 12.4 N/A N/A 52.5 Glass N/A 78.6 58.9 0.012 142.6 7.0 N/A N/A 52.5Plastic 0.125 21.6 38.9 0.012 94.5 5.3 N/A N/A 71.0 Plastic 0.125 19.538.3 0.012 57.4 2.5 N/A N/A 33.0 Plastic 0.125 19.5 40.3 0.012 45.7 1.7N/A N/A 17.0 Plastic 0.125 9.9 40.0 N/A 49.1 2.5 N/A N/A 26.6 Plastic0.125 4.7 35.0 N/A 19.4 1.4 N/A N/A 11.0 Plastic 0.125 9.3 33.3 N/A 39.41.8 N/A N/A 20.1 Plastic 0.125 7.7 32.0 N/A 18.3 1.1 N/A N/A 8.9 Plastic0.125 9.9 39.8 0.012 31.5 1.8 N/A N/A 18.1 Plastic 0.125 11.5 59.2 0.01232.5 1.5 35 82 22.1 Plastic 0.125 10.5 58.9 0.012 28.2 1.4 10 82 50.7Yellow Glass N/A 15.3 58.1 0.012 93.9 10.9 N/A N/A 60.0 Plastic 0.12525.9 44.1 N/A 103.4 6.4 N/A N/A 61.0 Glass N/A 53.0 56.5 0.012 114.5 8.3N/A N/A 57.0 Glass N/A 78.8 50.6 N/A 159.5 7.8 N/A N/A 57.0 Plastic0.125 77.8 50.6 N/A 153.8 2.7 N/A N/A 57.0 Plastic 0.125 5.5 55.2 N/A94.4 4.5 N/A N/A 62.0 Plastic 0.125 5.4 50.3 N/A 53.1 2.3 N/A N/A 32.0Plastic 0.125 4.5 52.2 N/A 30.1 1.2 N/A N/A 13.0 Plastic 0.125 9.7 41.40.012 39.0 3.0 N/A N/A 25.4 Plastic 0.125 3.6 38.8 0.012 13.8 1.9 N/AN/A 11.3 Plastic 0.125 8.7 35.1 0.012 34.1 2.7 N/A N/A 20.8 Plastic0.125 6.6 35.3 0.012 13.5 1.3 N/A N/A 8.7 Plastic 0.125 9.9 45.8 0.01231.8 2.3 N/A N/A 17.3 Plastic 0.125 19.3 51.5 0.012 32.6 1.9  3 82 47.8

Table 2 below includes a summary of laboratory test results using “cool”red light LED traffic lights and traditional light bulb traffic lights.The results show the energy consumed by each traffic light tested indifferent ambient environments (e.g., ambient temperature, relativehumidity, air velocity) and the associated surface temperatures of thelens. The results show that the existing “cool” red LED traffic lightsfail to maintain the surface temperature of the lens above the freezingtemperature about 32° F. at an ambient temperature of 10° F., which thetraditional light bulb succeeds in doing. However, the traditional lightbulb also fails to do so when connected to the traffic control cabinethaving an ON time of only 3 sec.

TABLE 2 Control Cabinet Lens Ambient Air Lens Time Cycle Wattage LEDLens gap Temp.(° F.) RH velocity temp.(° F.) On Time (W) Color Material(inch) Avg. % (m/s) Avg. STD (Sec) (Sec) Avg. Red Plastic N/A 2.1 72.10.012 9.1 3.1 N/A N/A 10.4 LED Plastic N/A 39.6 90.3 0.012 49.4 1.4 N/AN/A 10.4 Plastic N/A 80.6 54.3 0.012 85.8 0.8 N/A N/A 10.4 Plastic N/A77.9 57.3 0.012 87.1 1.8 N/A N/A 10.4 Light Glass N/A 44.0 75.4 0.012122.5 25.1 N/A N/A 60.0 Bulb Glass N/A 80.8 55.2 0.012 126.0 14.8 N/AN/A 60.0 Glass N/A 80.0 53.9 0.012 163.1 23.3 N/A N/A 60.0 Glass N/A23.5 52.3 0.012 105.7 24.6 N/A N/A 60.0 Glass N/A 8.3 62.6 0.012 33.04.3 10 82 60.0 Glass N/A 9.2 54.8 0.012 25.1 1.8  3 82 60.0

It should be appreciated that the embodiments described herein may berelied upon for both new and retrofit installations. The embodiments maybe used for placement of conventional outdoor lighting fixtures withoutthe need for extra installations other than “re-lamping”. By design, theembodiments do not alter the functions and sizes of existing lightingfixtures. In many cases, there is also no need to change the supportingelectrical devices due to no increases in power consumption. Further,the use of LED light sources may actually lower maintenance costs giventhe long life of LEDs.

Although embodiments have been described herein in detail, thedescriptions are by way of example. The features of the embodimentsdescribed herein are representative and, in alternative embodiments,certain features and elements may be added or omitted. Additionally,modifications to aspects of the embodiments described herein may be madeby those skilled in the art without departing from the spirit and scopeof the present invention defined in the following claims, the scope ofwhich are to be accorded the broadest interpretation so as to encompassmodifications and equivalent structures.

At least the following is claimed:
 1. A lighting fixture, comprising: alens; a heat exchanger including at least one aperture through the heatexchanger; a housing that secures the lens and the heat exchanger atrespective positions with facing surfaces thereof in proximity to eachother; a light source secured to the heat exchanger; and at least onelight fiber cable that extends from the light source at a first distalend to the at least one aperture at a second distal end.
 2. The lightingfixture according to claim 1, wherein: the light source comprises aplurality of light emitting diode (LED) light sources mounted on theheat exchanger for substantially uniform conduction of heat throughoutthe heat exchanger.
 3. The lighting fixture according to claim 1,wherein: the heat exchanger comprises a mounting niche formed at aproximate center of the heat exchanger for conduction of heat from theproximate center; and the light source is mounted in the mounting niche.4. The lighting fixture according to claim 1, wherein: the housingsecures the lens and the heat exchanger with a space between the facingsurfaces thereof; and the space is substantially uniform between thefacing surfaces.
 5. The lighting fixture according to claim 1, whereinthe facing surfaces of the lens and the heat exchanger contact eachother.
 6. The lighting fixture according to claim 1, further comprisinga light diffuser at the second distal end of the at least one lightfiber cable.
 7. The lighting fixture according to claim 1, wherein: theat least one aperture through the heat exchanger comprises a pluralityof apertures through the heat exchanger; the plurality of apertures arespaced apart across a major surface of the heat exchanger; the at leastone light fiber cable comprises a light fiber bundle comprising aplurality of light fiber cables; and each of the light fiber cablesextends from the light source at a first distal end to a correspondingone of the plurality of apertures at a second distal end.
 8. Thelighting fixture according to claim 1, wherein the heat exchangercomprises a passive heat exchanger formed of one of copper, aluminum, analuminum-copper alloy, iron, or steel.
 9. The lighting fixture accordingto claim 1, wherein the heat exchanger comprises one or more fins forconduction of heat away from the light source.
 10. A lighting fixture,comprising: a lens; a heat exchanger secured by a housing in proximityto the lens, the heat exchanger including at least one aperture throughthe heat exchanger; a light emitting diode (LED) light source secured tothe heat exchanger; a light collector that collects light from the LEDlight source; and at least one light fiber cable that extends from thelight collector at a first distal end to the at least one aperture at asecond distal end.
 11. The lighting fixture according to claim 10,wherein: the LED light source comprises a plurality of LED lightsources; and each of the plurality of LED light sources is mounted at arespective location on the heat exchanger.
 12. The lighting fixtureaccording to claim 10, wherein: the heat exchanger comprises a mountingniche; and the LED light source is mounted in the mounting niche. 13.The lighting fixture according to claim 10, wherein the housing securesthe lens and the heat exchanger at respective positions with a spacebetween facing surfaces thereof.
 14. The lighting fixture according toclaim 10, wherein the housing secures the lens and the heat exchanger atrespective positions with contact between facing surfaces thereof. 15.The lighting fixture according to claim 10, further comprising a lightdiffuser at the second distal end of the at least one light fiber cable.16. The lighting fixture according to claim 10, wherein: the at leastone aperture through the heat exchanger comprises a plurality ofapertures through the heat exchanger; the plurality of apertures arespaced apart across a major surface of the heat exchanger; the at leastone light fiber cable comprises a light fiber bundle comprising aplurality of light fiber cables; and each of the light fiber cablesextends from the light source at a first distal end to a correspondingone of the plurality of apertures at a second distal end.
 17. A lightingfixture, comprising: a lighting fixture housing; a lens secured by thelighting fixture housing; a heat exchanger secured by the lightingfixture housing in proximity to the lens to conduct heat into the lens,the heat exchanger including a plurality of apertures through the heatexchanger; a light source secured to the heat exchanger; and a lightfiber bundle including a plurality of light fiber cables, at least oneof the plurality of light fiber cables extending from the light sourceat a first distal end to a corresponding one of the plurality ofapertures at a second distal end and including a diffuser at the seconddistal end.
 18. The lighting fixture according to claim 17, wherein: thelight source comprises a plurality of light emitting diode (LED) lightsources; and each of the plurality of LED light sources is mounted at arespective location on the heat exchanger for substantially uniformconduction of heat throughout the heat exchanger.
 19. The lightingfixture according to claim 17, wherein the lighting fixture housingsecures the lens and the heat exchanger at respective positions with aspace between facing surfaces thereof.
 20. The lighting fixtureaccording to claim 19, wherein the lens includes a semispherical surfacearea and the space between the facing surfaces of the lens and the heatexchanger is substantially uniform over the facing surfaces.